Question

If x+y = z and y−z=x which of the following must be equal to z?

Answer 1

ANSWER

(C) y

EXPLANATION

We have two equations:

The first one is

$x + y = z...(1)$

The second equation is

$y - z = x...(2)$

Let us make z the subject of this second equation:

$\implies \: -x +y = z...(3)$

We now add equation (1) and (3) to get:

$(-x + x) + (y + y) = z + z$

We simplify to get:

$0+2y= 2z$

$2y= 2z$

Divide throu by 2.

$\frac{2y}{2} = \frac{2z}{2}$

$y= z$

$\therefore \: z = y$

The correct answer is C